2 * CTR with CBC-MAC Protocol (CCMP)
3 * Copyright (c) 2010, Jouni Malinen <j@w1.fi>
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
9 #include "utils/includes.h"
11 #include "utils/common.h"
12 #include "common/ieee802_11_defs.h"
13 #include "crypto/aes.h"
17 static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
18 u8 *aad, size_t *aad_len, u8 *nonce)
21 int qos = 0, addr4 = 0;
26 fc = le_to_host16(hdr->frame_control);
27 stype = WLAN_FC_GET_STYPE(fc);
28 if ((fc & (WLAN_FC_TODS | WLAN_FC_FROMDS)) ==
29 (WLAN_FC_TODS | WLAN_FC_FROMDS))
32 if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
33 fc &= ~0x0070; /* Mask subtype bits */
38 qc = (const u8 *) (hdr + 1);
41 nonce[0] = qc[0] & 0x0f;
43 } else if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_MGMT)
44 nonce[0] |= 0x10; /* Management */
46 fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
48 WPA_PUT_LE16(aad, fc);
50 os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
52 seq = le_to_host16(hdr->seq_ctrl);
53 seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
54 WPA_PUT_LE16(pos, seq);
57 os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
58 pos += addr4 * ETH_ALEN;
61 if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
69 os_memcpy(nonce + 1, hdr->addr2, ETH_ALEN);
70 nonce[7] = data[7]; /* PN5 */
71 nonce[8] = data[6]; /* PN4 */
72 nonce[9] = data[5]; /* PN3 */
73 nonce[10] = data[4]; /* PN2 */
74 nonce[11] = data[1]; /* PN1 */
75 nonce[12] = data[0]; /* PN0 */
79 static void xor_aes_block(u8 *dst, const u8 *src)
90 u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
91 const u8 *data, size_t data_len, size_t *decrypted_len)
93 u8 aad[2 + 30], nonce[13];
95 u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
97 const u8 *m, *mpos, *mic;
103 if (data_len < 8 + 8)
106 plain = os_malloc(data_len + AES_BLOCK_SIZE);
110 aes = aes_encrypt_init(tk, 16);
117 mlen = data_len - 8 - 8;
118 last = mlen % AES_BLOCK_SIZE;
120 os_memset(aad, 0, sizeof(aad));
121 ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce);
122 WPA_PUT_BE16(aad, aad_len);
123 wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
124 wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
126 /* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */
128 /* A_i = Flags | Nonce N | Counter i */
129 a[0] = 0x01; /* Flags = L' */
130 os_memcpy(&a[1], nonce, 13);
134 mic = data + data_len - 8;
135 wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8);
136 /* U = T XOR S_0; S_0 = E(K, A_0) */
137 WPA_PUT_BE16(&a[14], 0);
138 aes_encrypt(aes, a, x);
139 for (i = 0; i < 8; i++)
140 t[i] = mic[i] ^ x[i];
141 wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8);
143 /* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */
146 for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) {
147 WPA_PUT_BE16(&a[14], i);
148 /* S_i = E(K, A_i) */
149 aes_encrypt(aes, a, ppos);
150 xor_aes_block(ppos, mpos);
151 ppos += AES_BLOCK_SIZE;
152 mpos += AES_BLOCK_SIZE;
155 WPA_PUT_BE16(&a[14], i);
156 aes_encrypt(aes, a, ppos);
157 /* XOR zero-padded last block */
158 for (i = 0; i < last; i++)
161 wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);
164 /* B_0: Flags | Nonce N | l(m) */
165 b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
166 os_memcpy(&b[1], nonce, 13);
167 WPA_PUT_BE16(&b[14], mlen);
169 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
170 aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
172 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
173 xor_aes_block(aad, x);
174 aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */
176 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
178 xor_aes_block(&aad[AES_BLOCK_SIZE], x);
179 aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
183 for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) {
184 /* X_i+1 = E(K, X_i XOR B_i) */
185 xor_aes_block(x, ppos);
186 ppos += AES_BLOCK_SIZE;
187 aes_encrypt(aes, x, x);
190 /* XOR zero-padded last block */
191 for (i = 0; i < last; i++)
193 aes_encrypt(aes, x, x);
196 aes_encrypt_deinit(aes);
198 if (os_memcmp(x, t, 8) != 0) {
199 u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
200 wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR
201 " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
202 MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
204 WLAN_GET_SEQ_SEQ(seq_ctrl),
205 WLAN_GET_SEQ_FRAG(seq_ctrl));
206 wpa_hexdump(MSG_DEBUG, "CCMP decrypted", plain, mlen);
211 *decrypted_len = mlen;
216 void ccmp_get_pn(u8 *pn, const u8 *data)
218 pn[0] = data[7]; /* PN5 */
219 pn[1] = data[6]; /* PN4 */
220 pn[2] = data[5]; /* PN3 */
221 pn[3] = data[4]; /* PN2 */
222 pn[4] = data[1]; /* PN1 */
223 pn[5] = data[0]; /* PN0 */
227 u8 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
228 u8 *pn, int keyid, size_t *encrypted_len)
230 u8 aad[2 + 30], nonce[13];
232 u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
234 u8 *crypt, *pos, *ppos, *mpos;
236 struct ieee80211_hdr *hdr;
239 if (len < hdrlen || hdrlen < 24)
242 last = plen % AES_BLOCK_SIZE;
244 crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE);
248 os_memcpy(crypt, frame, hdrlen);
249 hdr = (struct ieee80211_hdr *) crypt;
250 hdr->frame_control |= host_to_le16(WLAN_FC_ISWEP);
251 pos = crypt + hdrlen;
252 *pos++ = pn[5]; /* PN0 */
253 *pos++ = pn[4]; /* PN1 */
254 *pos++ = 0x00; /* Rsvd */
255 *pos++ = 0x20 | (keyid << 6);
256 *pos++ = pn[3]; /* PN2 */
257 *pos++ = pn[2]; /* PN3 */
258 *pos++ = pn[1]; /* PN4 */
259 *pos++ = pn[0]; /* PN5 */
261 aes = aes_encrypt_init(tk, 16);
267 os_memset(aad, 0, sizeof(aad));
268 ccmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce);
269 WPA_PUT_BE16(aad, aad_len);
270 wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
271 wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
274 /* B_0: Flags | Nonce N | l(m) */
275 b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
276 os_memcpy(&b[1], nonce, 13);
277 WPA_PUT_BE16(&b[14], plen);
279 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
280 aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
282 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
283 xor_aes_block(aad, x);
284 aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */
286 wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
288 xor_aes_block(&aad[AES_BLOCK_SIZE], x);
289 aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
292 ppos = frame + hdrlen;
293 for (i = 0; i < plen / AES_BLOCK_SIZE; i++) {
294 /* X_i+1 = E(K, X_i XOR B_i) */
295 xor_aes_block(x, ppos);
296 ppos += AES_BLOCK_SIZE;
297 aes_encrypt(aes, x, x);
300 /* XOR zero-padded last block */
301 for (i = 0; i < last; i++)
303 aes_encrypt(aes, x, x);
308 /* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */
310 /* A_i = Flags | Nonce N | Counter i */
311 a[0] = 0x01; /* Flags = L' */
312 os_memcpy(&a[1], nonce, 13);
314 ppos = crypt + hdrlen + 8;
316 /* crypt = msg XOR (S_1 | S_2 | ... | S_n) */
317 mpos = frame + hdrlen;
318 for (i = 1; i <= plen / AES_BLOCK_SIZE; i++) {
319 WPA_PUT_BE16(&a[14], i);
320 /* S_i = E(K, A_i) */
321 aes_encrypt(aes, a, ppos);
322 xor_aes_block(ppos, mpos);
323 ppos += AES_BLOCK_SIZE;
324 mpos += AES_BLOCK_SIZE;
327 WPA_PUT_BE16(&a[14], i);
328 aes_encrypt(aes, a, ppos);
329 /* XOR zero-padded last block */
330 for (i = 0; i < last; i++)
334 wpa_hexdump(MSG_EXCESSIVE, "CCMP T", x, 8);
335 /* U = T XOR S_0; S_0 = E(K, A_0) */
336 WPA_PUT_BE16(&a[14], 0);
337 aes_encrypt(aes, a, b);
338 for (i = 0; i < 8; i++)
339 ppos[i] = x[i] ^ b[i];
340 wpa_hexdump(MSG_EXCESSIVE, "CCMP U", ppos, 8);
342 wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen);
344 aes_encrypt_deinit(aes);
346 *encrypted_len = hdrlen + 8 + plen + 8;